stream-utils: fixed file name

1 files changed, 0 insertions, 180 deletions

diff --git a/src/clojure/contrib/stream-utils.clj b/src/clojure/contrib/stream-utils.clj
deleted file mode 100644
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--- a/src/clojure/contrib/stream-utils.clj
+++ /dev/null
@@ -1,180 +0,0 @@
-;; Stream utilities
-
-;; by Konrad Hinsen
-;; last updated January 25, 2009
-
-;; Note: this module is at least as experimental as Clojure's stream
-;; facilities. It may change significantly, change name, or disappear
-;; in the future. Don't rely on it for your applications. I put this
-;; module in clojure.contrib so that it can serve as a testground and
-;; a basis for discussions ont the group.
-
-;; Copyright (c) Konrad Hinsen, 2009. All rights reserved.  The use
-;; and distribution terms for this software are covered by the Eclipse
-;; Public License 1.0 (http://opensource.org/licenses/eclipse-1.0.php)
-;; which can be found in the file epl-v10.html at the root of this
-;; distribution.  By using this software in any fashion, you are
-;; agreeing to be bound by the terms of this license.  You must not
-;; remove this notice, or any other, from this software.
-
-(ns clojure.contrib.stream-utils
-  (:use [clojure.contrib.monads]))
-
-;; Streams
-
-; Stream of integers
-(defn int-stream
-  "Return a stream of integers starting from init and incrementing by step
-   until end, the first value not returned. The defaults are 0, 1, and nil,
-   where nil stands for an infinite stream."
-  ([] (int-stream 0 1 nil))
-  ([init] (int-stream init 1 nil))
-  ([init step] (int-stream init step nil))
-  ([init step end]
-   (let [n (into-array [init])]
-     (stream
-      (fn [eos]
-	(let [current (aget n 0)]
-	  (if (or (nil? end) (< current end))
-	    (do
-	      (aset n 0 (+ current step))
-	      current)
-	    eos)))))))
-
-;; Stream transformers
-
-(defn drop-first
-  "Return a stream that returns the elements of s except for the first n ones."
-  [n s]
-  (let [eos (Object.)
-	iter (stream-iter s)
-	gen (fn [eos] (next! iter eos))]
-    (doseq [_ (range n)] (gen eos))
-    (stream gen)))
-
-;; Monadic stream transformers
-
-; Generator monad
-;
-; This monad represents computations with generators, as defined for
-; Clojure streams: a function of one argument, an end-of-stream value,
-; that returns at each call the "next" value of the stream, until the
-; end of the stream is reached, and from then on it returns the supplied
-; eos value forever. This monad permits the simple composition of such
-; generators.
-;
-; The use of generators instead of streams as the basis of this monad
-; has two reasons:
-; 1) It is not possible to pass around a stream such that each
-;    monadic computation step takes one item of it, because there can
-;    be only one iterator per stream.
-; 2) One could use iterators instead of generators as the monadic
-;    values, even with minimal changes, but each computational step
-;    in the monad would then create a new stream and a new iter,
-;    adding overhead for no apparent benefit.
-
-(defmonad generator
-   "Monad describing stream-transforming computations. The monadic
-    values are generator functions."
-   [m-result (fn m-result-generator [v]
-	       (fn [eos] v))
-    m-bind   (fn m-bind-generator [mv f]
-               (fn [eos]
-		 (let [v (mv eos)]
-		   (if (identical? v eos)
-		     eos
-		     ((f v) eos)))))
-    ])
-
-; A macro for defining stream transformers using the generator monad.
-; It wraps the input streams into iters-that-look-like-generators,
-; and converts the resulting generator into a stream.
-(defmacro stream-transformer
-  [stream-args & body]
-  `(stream (let [~stream-args (map stream-iter ~stream-args)]
-	     (with-monad generator ~@body))))
-
-
-; Derive a variant of the generator monad that permits the
-; use of :when conditions. Invalid values in the output are
-; represented by ::skip, which is filtered out in the end
-; by applying remove-skip. The macro stream-transformer-cond
-; takes care of all these administrative details.
-(def generator-cond (maybe-t generator ::skip :m-plus-from-maybe))
-
-(defn remove-skip [g]
-  (fn [eos]
-    (loop [v (g eos)]
-      (if (identical? v ::skip)
-	(recur (g eos))
-	v))))
-
-(defmacro stream-transformer-cond
-  [stream-args & body]
-  `(stream (remove-skip
-    (let [~stream-args (map stream-iter ~stream-args)]
-      (with-monad generator-cond ~@body)))))
-
-
-;; Some examples of monadic stream transformers
-
-(defn skip-s [s]
-  "Return a stream that skips every second item of s"
-  (stream-transformer [s]
-    (domonad
-      [x1 s
-       x2 s]
-      x2)))
-
-(defn partition-s [n s]
-  "Return a stream in which each element is a sequence of n consecutive
-   elements of the input stream s."
-  (stream-transformer [s]
-    (m-seq (replicate n s))))
-
-; Map a function on streams.
-; Map has to be defined by an explicit expression for every number of
-; arguments because the m-lift macro requires a constant as its first
-; argument.
-(defn map-s
-  "Return a stream of the results of applying f on one item of each
-   input sequence."
-  ([f s]
-   (stream-transformer [s]
-     ((m-lift 1 f) s)))
-  ([f s1 s2]
-   (stream-transformer [s1 s2]
-     ((m-lift 2 f) s1 s2)))
-  ([f s1 s2 s3]
-   (stream-transformer [s1 s2 s3]
-     ((m-lift 3 f) s1 s2 s3)))
-  ([f s1 s2 s3 s4]
-   (stream-transformer [s1 s2 s3 s4]
-     ((m-lift 4 f) s1 s2 s3 s4)))
-  ([f s1 s2 s3 s4 s5]
-   (stream-transformer [s1 s2 s3 s4 s5]
-     ((m-lift 5 f) s1 s2 s3 s4 s5))))
-
-(defn filter-s [p s]
-  "Return a stream consisting of the elements of s that satisfy predicate p."
-  (stream-transformer-cond [s]
-    (domonad
-     [x s :when (p x)]
-     x)))
-
-(comment
-
-; Some example expressions
-
-(take 10 (drop-first 5 (int-stream)))
-
-(take 10 (skip-s (int-stream)))
-
-(take 10 (partition-s 3 (int-stream)))
-
-(take 10 (map-s inc (int-stream)))
-(take 10 (map-s + (int-stream) (map-s inc (int-stream))))
-
-(take 10 (filter-s #(zero? (rem % 3)) (int-stream)))
-
-)
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